The present invention is generally related to methods and apparatus for the assembly of display panels such as liquid crystal display (LCD) devices, and in particular, to a method and apparatus for bonding one or more layers of glass, plastic, or other material of appropriate optical properties to a display module.
Display panels, such as liquid crystal display modules, are widely used in all parts of modern technology, including such areas as consumer electronics, computer equipment, industrial machinery controls, automobiles and aerospace applications. These display panels may include one or more layers of material disposed over the raw liquid crystal display module. For example, a protective overlay is most often desired for protection of the raw liquid crystal display module from mechanical and environmental forces. Raw display panes such as LCD modules, for example, usually have no protection for the top polarizer layer and the underlying glass layers. The protective overlay can provide additional features such as support for anti-reflective coatings which can enhance the display visibility under varying lighting conditions. Other layers of material which may be disposed over the raw liquid crystal display module include touch-sensitive panels, optical filers, heaters, and EMI shields.
Since this bonding process is for visible displays, the bonding layer which secures each layer of material must be transparent and completely free of optical defects such as entrapped dirt and air bubbles. Freedom from entrapped air bubbles are a particular advantage of the invention. Using traditional bonding techniques and apparatus, a bonding material such as an adhesive is utilized to secure a layer such as a protective overlay to a display module is applied in a bead first to only one surface, either the top surface of the display module or the underside of the protective overlay, followed by pressing another, un-wetted surface against the bead, and is likely to trap air bubbles when the second un-wetted surface first touches the bead of bonding material.
Accordingly, it would be advantageous to provide a method and apparatus for the bonding of one or more material layers to a display module surface which yields a resulting assembly which is transparent and completely free of optical defects such as entrapped dirt and air bubbles.